Campaign finance violations seem clear cut corruption. (Again, not mandatory jail sentencing. But jail is on the table.)
Perjury and contempt obviously need the capacity to put someone in jail. I resolve the moral discrepancy with their short durations. Theft is the elephant in the room for this framework, and I don't have a good answer for it.
There are campaign finance violations that I would not consider corruption in the quid-pro-quo sense but are still illegal. I am sympathetic to your line of reasoning though I think the current sentencing guidelines are by and large fair. I would like to see less emphasis on "intended loss" and more rewards for making victims whole.